When astronauts are to perform extra vehicular activities (EVA) outside of a spacecraft, they require protective space suits for protecting them against the direct influences and conditions prevailing in outer space. These influences and conditions in outer space include, for example, the potentially very great dangers that could be caused by impact of micrometeorites or other space "garbage" radioactive radiation, particle radiation, or atomic oxygen, as well as attack by aggressive chemical substances. Such aggressive substances may, for example, stem from the remainder or decomposition components of rocket fuel used by the position control rockets of a spacecraft, for example. Additionally, a protective space suit must provide sufficient thermal protection against the wide range of temperatures prevailing in outer space. Further, the fabric for making such space suits must be especially resistant to gas permeation. Thus, the fabric must be especially resistant to friction and mechanical wear and tear as well as electrical static charges and discharges. Such static electrical charging and discharging must be prevented because these phenomena may cause microscopically small holes in the space suit. Furthermore, the fabric or material used in such space suits must be extremely resistant to all types of electromagnetic radiation and any possible degrading influence caused by chemicals that may contact the suit during EVA in space, or that may be used for cleaning and/or for decontaminating such suits.
It is also very important that protective fabric used in a space suit, or as a protective shielding in space is sufficiently flexible that it may be folded and draped, e.g. to use as a shielding material, and that it forms a comfortable space suit. If the fabric is too stiff, or becomes stiff when subjected to outer space conditions, then a suit or other protective clothing will be uncomfortable and clumsy and will not allow the effective and efficient performance of EVA. Furthermore, a more flexible fabric is easier to handle during its manufacture, storage, distribution, etc., when manufacturing protective clothing therefrom or when shaping protective shielding from the fabric.
A textile fabric to be used in fire protection suits or other protective clothing such as fire or chemical protection gloves, jackets, or headgear, must meet many of the same requirements described above regarding protective space suits. For example, fabric used to make fire protective clothing must be flexible and comfortable, must provide good thermal insulation and must resist degrading effects of aggressive chemicals and mechanical wear and abrasion.
U.S. Pat. No. 4,923,741 discloses a laminar structure for use as a protective covering such as a protective space suit. Such a laminar structure comprises an outer layer known commercially as ORTHOFABRIC, including a surface layer of woven, expanded. tetrafluoroethylene fibers known under the Tradename GORETEX. Below the surface layer, the ORTHOFABRIC includes a layer of meta- or para-aramide fibers (polyparaphenyleneterephthalamide) known under the Tradenames NOMEX or KEVLAR. The outer GORETEX layer is intended to protect against atomic oxygen and against abrasions while the lower layer shall provide for the mechanical strength and resistance against mechanical wear and tear. The disclosed fabric also contains electrically conductive fibers to provide for electrostatic charge dispersion and a discharge path for static or other electrical charges. Additionally, the known fabric is provided with a coating of silicone or Teflon-FEP (Tetrafluoroethylene-Fluoroethylene-Propylene). The Teflon-FEP coating shall protect against chemical influences of spacecraft fuel remainders.
In addition to the ORTHOFABRIC layer, the disclosed laminar structure includes middle layers of thermal insulation, a protective layer against short wave electromagnetic radiation as well as an inner layer for protecting the wearer against abrasion as well as against mechanical damage, including protection against the above mentioned impacts of micrometeorites.